Romeo is a lean, well-built young boy of short stature, possessing prominent abdominal and pectoral muscles and, to a minor degree, biceps. He has straight, yet long and spiky dark purple hair. His bangs are particularly prominent, covering part of his forehead, with some smaller strands jutting outwards from the top of his head. He has large, dark eyes and a small, mildly round nose. His guild stamp is red and is on his left shoulder. Because of his appearance, many female characters considers him very attractive and handsome.

Romeo wears an attire that somewhat resembles Natsu Dragneel's, likely out of admiration for him and sadness for his supposed death. He wears a long, dark mahogany, sleeveless open jacket with lighter-colored edges that reaches to his low-thighs, revealing part of his muscular chest and held closed around his waist by a white sash, tied by a knot on his left hip. His legs are covered by loose, dark-green pants reaching down below his knees, paired with low, brown laced boots. Around his neck is a light-orange scarf adorned by a wavy motif, mirroring the one which Igneel gave Natsu, but being tied on the front in a large knot. His left forearm is wrapped in bandages while a dark yellow bracelet is worn around his right wrist.

Romeo is a cool, serious, mature, and clever young boy; his personality seems to be rare for boys of his age. He is also stubborn when it comes to not backing down from a tough fight, a trait he inherited from Natsu. Being a Fairy Tail Mage, he is a proud member of the guild who tries to defend its name and honor from anyone who insults it. Also, when he talks about or with his older guild or crew members, he ends their name in Nii or Nee honorifics, while addressing Wendy as "Wendy-chan". Despite his somber disposition, Romeo, is in fact, a very friendly, valiant and caring soul, willing to help others in need like Natsu; in a twist of irony, he doesn't inherit Natsu's recklessness, and takes his actions more carefully like Gray.

During his childhood, Romeo was a kind and good-hearted boy who loves his father very much. He takes pride in Macao's occupation as a Mage, and makes it his childhood dream to become a Mage himself. He also greatly admires Natsu, viewing him as an older brother figure and mentor. After Natsu disappears together with the Tenrou team on Tenrou Island and is believed to be dead along with everyone else on it, Romeo becomes a sullen, cynical youth who believes his father to be a coward for doing nothing to defend their guild, and doesn't smile throughout the missing Mages' absence until they return seven years later.

Because of his great maturity and sense of self-control, Romeo is much more respectful and appropriate towards girls around or above his age, much less his more older male guildmates who sometimes act like perverts; he is the only male allowed to bathe with the girls in hot springs because of his polite nature and the girls' likeness towards him (especially Erza, Lucy, Levy, Nami, Robin, Mirajane, Cana, and most of all, Wendy), much to his embarrassment, which, makes him very awkward around them at first. But after Wendy consulted him about his urges with women through her insecurity of being flat-chested and small, he feels at ease and now bathes with women without having any problems. Deep down, he is deeply shy and flustered around women and tries to conceal his urges no matter how difficult it is.

He has romantic feelings for Wendy Marvell since childhood, and has shown to grow further following the Tenrou team's seven year absence/return, which also prevented the aging of every member, including Wendy. Sometimes, he can be a bit dense when trying to admit his feelings towards her and constantly brushes off any interest pointed to him by his fellow guildmates, mainly Natsu, Happy, Gray or Gajeel.

Rainbow Fire: Romeo can use this type of Fire Magic, which allows him to create different-colored flames for different effects. By his claim, he has mastered five colored types of Rainbow Fire (I.e. blue, red, green, yellow and orange), while allowing his Purple Flare substitute for purple and indigo.

Blue Fire: A spell in which Romeo creates a blue-colored flame with cold properties.

Green Fire: A unique spell in which Romeo creates a green-colored hand for healing properties, as opposed to burning.

Orange Fire: Romeo creates some orange-colored flame with grappling abilities that is mainly used to render the target immobile, while also burning them.

Yellow Fire: A spell in which Romeo creates a yellow-colored flame hovering on his palm. This flame apparently gives off a strange smell.

Red Fire: A spell in which Romeo creates a red-colored flame in each of his palms. When he brings them together in a cup-like motion, the two flames creates a straight, fire-based stream that greatly damages his opponent, as well as causing a wide-range explosion.

Rainbow Fire: The user combines the different "colors" of their Rainbow Fire Magic into one, alleged, "deadliest flame". Upon hitting its target, it causes a large-ranged explosion.

Purple Flare: This is a variation of Fire Magic, which allows the user to create and manipulate specific purple flames, that cannot be extinguished by wind or water. He usually conjures it through his arms or the palm of his hands, and can use this magic in various ways, such as attacking, binding or supporting. It can also allow him to stick to objects for either swinging towards certain gaps that can't be reached on foot or to grab his enemies and pull them towards him, leaving them open for direct attacks.

Purple Net: The user summons forth a flame orb, which creates purple flare taking the form of ropes, ensnaring groups of people around them. The form of this spell differs depending on the user, as it can be used as a net rather than ropes.

Purple Bombardment: The user generates multiple balls of purple fire that sticks to the opponents before exploding with tremendous force.

Purple Bullet Fist: A powerful melee move, which Romeo engulfs his fist in purple flames to punch the target with great force aside from burning them. This move bares a striking resemblance to Natsu's Fire Dragon's Iron Fist, which he learned by watching Natsu using this move up close several times before.

Expert Hand-to-Hand Combatant: While only 13, Romeo is an adept unarmed combatant since his seven year timeskip training, developing a fighting style akin to Natsu's. He usually strikes with hands and elbows, at least - the legs. He is able to do some acrobatics, such as somersaults, evading attacks, owing to the reaction, as in the situation with Dan Straight. His blows are usually enhanced by Fire Magic, apparently making them stronger.

Enhanced Strength: Despite his small stature, Romeo possesses a high degree of strength that nearly matches that of Natsu's; he can shatter walls with kicks and punches, lift objects twice his own weight, and use a wooden table as a temporary weapon.

Enhanced Speed: Because of his size, Romeo is fast enough to close several meter distances between him and his opponent and strike before they have a chance to react.

Enhanced Reflexes: Romeo has been seen dodging and even catching high-speed projectiles when launched at him (for example, bullets), impressing even S-Class Mages the likes of Erza and Laxus, for a child to have such precise response timing.

Enhanced Endurance: Romeo's physical stamina and endurance are comparable to that of the finest Olympic-level athlete.

Enhanced Durability: Despite his age and small stature, Romeo has been seen taking numerous forces of great impact and still being able to stand up with just minor scratches.

Gifted Intellect: One of Romeo's most distinguishing traits is his intellect and natural talent. Between the seven year gap after the "disappearance" of Team Tenrou and Tenrou Island, Romeo is a young prodigy who quickly learned many things about the Magic World and having mastered two types of Fire Magic with relative ease. Aside from his knowledge, his intellect is also demonstrated in battle situations; he has great instinct against incoming danger, and intuition during combat. He is also a keen analyst, able to deduce the basic mechanics behind an opponent's attacks, and quickly figuring out its strength and weakness to better counter it. Romeo is always aware of his surroundings, and is also able to see through certain deceptions that even surprised Gray, Erza and Robin; by his claim. Even older figures like Jellal, Gildarts, and Sabo consider him a child genius, and Doranbolt, a member of the Magic Council, might consider him one of the most intelligence Mages in Earth Land; a theory that can be proven on certain occasions.

Great Magic Power: As a Mage of Fairy Tail, Romeo boasts a high level of magical energy. Throughout his countless adventures however, has increased his Magic Power even further, almost making him a potential S-Class Mage Candidate at such a young age. His Magic Power is violet in color.